1. Field of the Invention
The present invention relates to an increase in reliability against failures in a system using logical computers.
2. Description of the Prior Art
The advance of processor technology has enabled high-performance processors to be easily used. Conventionally, insufficient performance has been covered by running plural logical computers in parallel. With the advent of high-performance processors, however, performance has been satisfied and concerns are shifting to how to effectively use the high-performance processors. A logical computer function is one approach to the effective use of the high-performance processors. The logical computer function is technology for creating plural virtual computers from one physical computer.
For example, by assigning one physical processor to plural logical computers in a timesharing mode, software running on the logical computers can operate as if different physical computers existed. This function allows effective use of one high-performance physical processor. There is an example that further develops the logical computer function to provide higher reliability.
In U.S.005345590A, a method is described which builds a hot standby with two logical computers, and when one of them fails, switches to another logical computer to continue processing. The hot standby method is a method for achieving high reliability normally with different computers. According to this technology, two different computers are provided so that processing is normally performed by one computer, and if a failure occurs, switching is made to another standby computer without stopping processing. In U.S.005345590A, a hot standby is built between two logical computers created on an identical physical computer. This contributes to an increase in reliability of system level.
In Japanese Patent Laid-Open No. 2001-34495, a description is made of technology for preventing abnormal termination of processing of a duplexed processing device due to system switching by the saving of execution statuses and system switching based on predictions on failures of the processing device. There is such technology for predicting failures at hardware level.
In the U.S.005345590A, a description is made of a method which increases reliability by building a hot standby with two logical computers. According to this method, since standby logical computers are provided in advance for hot standby, computer resources are consumed for unpredictable failures.
In Japanese Patent Laid-Open No. 2001-34495, a description is made of a method for changing the operation of a duplexed device. According to this method, although failures are predicted, the device is assumed to be duplexed, and still computer resources are consumed.